This invention relates to a process for making an arylene sulfide ketone polymer.
The production of thermoplastic polymers is a major industry of the United States of America. It has been estimated that the production, in the United States, of a few of the more important thermoplastic polymers, approached forty-four billion pounds, or about twenty billion kilograms, in 1989.
Thermoplastic polymers are highly valued for their molding and processing characteristics. These characteristics make them highly desirable for the mass production of items such as pipes, films, fibers, dishes, utensils, automobile parts, beverage containers, and assorted other consumer items.
Thermoplastic polymers have the ability to be repeatedly softened when heated and hardened when cooled. This allows a recycling company to use thermoplastic waste products as building blocks for new and useful items. In contrast, thermosetting polymers do not have the ability to be repeatedly formed into other products. The reason is that thermosetting polymers cannot be remelted or remolded without destroying the original characteristics of the polymer.
Historically though, thermoplastic polymers tend to be inferior to thermosetting polymers in high temperature strength and chemical stability applications. However, in recent years a variety of thermoplastic polymers have been developed which can be employed at relatively high temperatures and/or under corrosive conditions.
However, these new resistant thermoplastic polymers also have problems. For example, these new polymers may have a molecular weight that is not high enough to maintain a good balance of physical properties, and consequently articles made from these polymers will not be as useful. This is why much research has been done to make a high molecular weight thermoplastic polymer which is both thermally and chemically resistant while maintaining the physical properties of the polymer.
Arylene sulfide ketone polymers are an example of this development. In particular, poly(phenylene sulfide ketone) (PPSK) is known in the art as a polymer which has a high melting point. Thus, PPSK is desired in applications requiring a high thermal resistance. For example, PPSK can be used for coatings on electrical wiring and as parts on automobile engines.
Arylene sulfide ketone polymers are also especially useful in applications where they reinforced with heat resistant fibers, filaments, or fillers, thus providing heat resistant reinforced structures. These structures show a degree of toughness and thermal resistance which makes them uniquely useful in the specialty applications required for space and defense work.
However, as stated before, these polymers suffer from problems which makes them difficult to work with. For example, these polymers tend to form low particle size solids during synthesis. These small particles can then become airborne which is undesirable. Additionally, the small particle size of the polymer can present a substantial separation problem to the polymer manufacturer.
This invention addresses these problems by presenting a process which gives a larger particle size polymer thereby reducing problems associated with a small particle size polymer. Furthermore, this invention provides a process to make a higher molecular weight polymer while substantially maintaining the desired physical characteristics of the polymer.